Mimamsasutra 3.2.18

For everywhere the conduct of the cultured is rooted in tradition; therefore, here too / Tradition is to be inferred, but that [inferred tradition] is sublated by directly perceived tradition.

In certain southern regions, cultured people marry the daughter of a maternal uncle. If it is said that this conduct is an authoritative means of valid cognition, because it is the conduct of the cultured, just like the conduct regarding the Holākā festival and the like;

No, because, being opposed to tradition, it is vitiated by the fallacy of contradiction [by a stronger authoritative source]. And likewise there is the traditional text:

"Having married the daughter of a maternal uncle, and likewise one belonging to the mother's clan,

And one of the same lineage-sages, having abandoned her, he should perform the cāndrāyaṇa penance." Thus.

And one should not suspect that tradition and conduct are of equal force on the ground that they are equal in inferring the Vedic source. For righteous conduct like the Holākā festival and the like cannot infer a Vedic source in the manner of the tradition of Manu and others. For cultured persons of the present time cannot, like Manu and others, directly perceive with divine knowledge the Veda that is remote in space and time, by which conduct of the cultured could infer a Vedic source. And any cultured person anywhere, in a specific country and at a specific time, is able to see some traditional text that is the source of conduct like the Holākā and the like. Therefore, by the conduct of the cultured only a traditional text can be inferred, not a direct Vedic statement. And an inferred traditional text is sublated by a conflicting, directly perceived traditional text. Hence they say: